A Black Hole at the Centre of our Galaxy

What lies at the centre of the Milky Way? For a long time, astronomers have suspected that a black hole lurks at the heart of our Galaxy, but could not be sure. After years of regular monitoring of the Galactic Centre with ESO telescopes at the La Silla Paranal Observatory, scientists finally obtained conclusive evidence.

Stars at the centre of the Milky Way are so densely packed that special imaging techniques such as Adaptive Optics were needed to boost the resolution of the VLT. Astronomers were able to watch individual stars with unprecedented accuracy as they moved around the Galactic Centre. Their paths conclusively showed that they must be orbiting in the immense gravitational grip of a supermassive black hole, almost three million times more massive than our Sun.The VLT observations also revealed flashes of infrared light emerging from the region at regular intervals. Whilst the exact cause of this phenomenon remains unknown, observers have suggested the black hole may be spinning rapidly. Whatever is happening, the black hole's life is not all peace and quiet. See ESO Press Releases eso1332, eso1151, eso0846, eso0226 and eso0330

Astronomers also use the VLT to peer into the centres of galaxies beyond our own, where they again find clear signs of supermassive black holes. In the active galaxy NGC 1097, they could see with unprecedented detail a complex network of filaments spiralling down to the centre of the galaxy and possibly providing for the first time a detailed view of the channelling process of matter, from the main part of the galaxy down to its very end in the nucleus. See ESO Press Releases eso0109, eso0319, eso0414, eso0529, and eso0534.

The climax of a 26-year-long observation campaign using the VLT was the confirmation in 2018 of the effects predicted by Einstein’s general relativity on the motion of a star passing through the extreme gravitational field near the supermassive black hole in the centre of our Galaxy. See ESO Press Release eso1825.

"We needed even sharper images to settle the issue of whether any configuration other than a black hole is possible and we counted on the ESO VLT to provide those. Now the era of observational black hole physics has truly begun!"

Reinhard Genzel, Director at the Max-Planck Institute for Extraterrestrial Physics